JPH06181063A - Hydrogen storage alloy electrode - Google Patents

Abstract

PURPOSE:To provide an inexpensive hydrogen storage alloy electrode by which falling or separation of an active material and a short circuit can be prevented. CONSTITUTION:A hydrogen storage alloy electrode is constituted by applying an active material formed by mixing an electrically conductive agent and a binder in hydrogen storage alloy powder in a slurry shape to both sides of an electrode substrate 1 or by binding into a sheet shape. Rectangular through- holes 4 having a pyramid shape projection are arranged alternately on an opposite direction in a core body of this electrode substrate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrogen storage alloy electrode used in a nickel metal hydride battery.

[0002]

2. Description of the Related Art As a conventional hydrogen storage alloy electrode, a substrate core having a three-dimensional structure, such as a nickel metal fiber porous body or a foam metal porous body, or a two-dimensional substrate core body such as a punching sheet, expanded metal or a mesh net. In addition, an electrode has been developed by filling, coating, or binding a slurry-like active material in which a hydrogen storage alloy is mixed with a conductive agent and a binder.

The former substrate core is a complicated manufacturing method in which, for example, a polyurethane foam is nickel-plated, and then the urethane, which is the core material, is baked and removed to produce a nickel foam porous body. Quite expensive. On the other hand, the latter substrate core has the advantages that its manufacturing method is simpler and less expensive than the former, and thus has been actively developed in recent years.

[0004]

However, these two-dimensional substrates have a weaker force for holding the active material on the substrate as compared with the three-dimensional porous substrate, and thus the life of the active material is shortened due to dropping or peeling of the active material. The increase in the distance d between the substance and the current collector (substrate) causes a decrease in the utilization rate of the active material. Further, when the expanded metal is used as the substrate, it is difficult to eliminate burrs and the like when the electrode is cut into a predetermined size, and as a result, there is a problem that a short circuit occurrence rate is high when the battery is assembled. The present invention has been made in view of the above problems, and provides an inexpensive hydrogen storage electrode in which the active material is prevented from falling off, peeling off, and a short circuit.

[0005]

The hydrogen storage alloy electrode of the present invention is applied to both sides of a substrate by applying an active material obtained by mixing a hydrogen storage alloy powder with a conductive agent and a binder in the form of slurry or binding them into a sheet. In the hydrogen storage alloy electrode, a rectangular through hole having pyramidal protrusions alternately provided in opposite directions is provided on the front and back of a nickel sheet, a copper sheet, or a nickel-plated iron sheet that is the core of the electrode substrate. It is what

[0006]

The operation of the present invention will be described with reference to FIGS.
A description will be given based on (an example of a conventional method). According to the invention,
As shown in FIG. 1, since the rectangular through holes 4 are regularly arranged in the substrate core body 1 and the pyramidal protrusions 5 are densely arranged alternately on both surfaces of the substrate, the active material 2 on both sides of the core body 2 is formed. In this case, the binding is strengthened, and it is possible to effectively prevent the active material from falling off or peeling off when a conventional two-dimensional smooth core such as a punching sheet is used as the substrate as shown in FIG.
In addition, since the cross section of the core of the through hole (cross section taken along the line AA in FIG. 1) has a "c-shaped" structure in the thickness direction of the electrode, the distance between the current collector (substrate core) and the active material is reduced by the conventional method. (Cross-section taken along line BB in FIG. 3), it also has the effect of becoming shorter, and it is possible to improve the holding power of the active material and at the same time improve the active material utilization rate.

[0007]

EXAMPLES Examples of the present invention will be described in detail below. Material thickness 20
Using a nickel sheet or copper sheet of ~ 80 μm as a core, and passing the core between two cutter rolls with two pyramid-shaped needle-like protrusions cut on the surface,
Pyramidal needle-shaped protrusions were alternately penetrated in opposite directions to open the holes and simultaneously form pyramidal protrusions. By adjusting the clearance between the cutter rolls for the square aperture diameter and the protrusion height, a substrate core having a square aperture diameter of 500 μm and a protrusion height of about 300 μm was produced. When an iron sheet was used, it was subsequently electroplated with about 3 μm of nickel in a well-known nickel sulfate bath.

As a comparative example, an iron sheet having a material thickness of 80 μm was circularly perforated with a diameter of 1.4 mm by a conventional method to prepare a punching sheet. The substrate core prepared in this manner was coated with a hydrogen-absorbing alloy powder mixed with a nickel powder conductive agent and a Teflon binder to form a slurry, which was dried and pressed to form a 0.5 mm-thick hydrogen film. A storage alloy electrode was produced.

A cross-sectional view of a substrate of the present invention and a nickel electrode using the same and a conventional comparative example are shown in FIGS. In the electrode of the present invention, as shown in the electrode cross-sectional view of FIG. 2, the core body of the through hole has a "V-shaped" structure in the electrode thickness direction. As a result, as shown in FIG. 4, which is a conventional comparative example, the cross section of the core body was different from the smooth one, so that the holding force of the active material layer was improved, and the falling and peeling were effectively prevented. In addition, the above
Due to the "H-shaped" structure, the distance between the active material and the current collector (substrate core) in the electrode thickness direction is shortened, so improvement of the active material utilization rate and high rate discharge performance is recognized compared to conventional electrodes. Was given.

The height of the pyramidal protrusions densely arranged on both sides of the substrate core body of the present invention is as large as possible within the range where the pyramidal protrusions are not exposed from the electrode surface and do not cause a short circuit or the like to prevent the active material from falling off or peeling. Since it is effective, it has been found that it is suitable to set it to about 2/5 of the electrode thickness.

As described above, according to the present invention, the hydrogen storage alloy electrode in which the active material is effectively prevented from falling off, peeling off, short-circuiting or the like by using the electrode substrate core manufactured by the inexpensive and simple manufacturing method. , Its industrial value is extremely high.

[Brief description of drawings]

FIG. 1 is a plan view of an electrode substrate of the present invention.

2 is a cross-sectional view of the electrode of the present invention, which is taken along line AA of FIG.
It corresponds to a section.

FIG. 3 is a plan view of a conventional electrode substrate.

FIG. 4 is a cross-sectional view of a conventional electrode, which corresponds to a portion BB in FIG.

[Explanation of symbols]

 1 substrate 2 active material 3 electrode 4 through hole 5 pyramidal protrusion

Claims (2)

[Claims] 1. A hydrogen storage electrode, which is formed by applying an active material prepared by mixing a hydrogen storage alloy powder with a conductive agent and a binder in the form of slurry on both sides of an electrode substrate, or forming a sheet to bind the active material. A hydrogen storage alloy electrode, characterized in that the core of the electrode substrate is provided with rectangular through holes having pyramidal protrusions alternately in opposite directions. 2. The core material is a nickel metal sheet, a copper sheet,
2. The hydrogen storage alloy electrode according to claim 1, which is a nickel-plated iron sheet and is a core body in which the height of the pyramidal protrusion is not more than ⅕ of the electrode thickness.